So far I would say.....
Horror: these lines ideally belong together in an Omnibus, some are not very popular and some are too short to reprint on their own.

Red Wolf aka western, I have to agree, western in general it doesn't hold much interest and neither does Skull. 
Shanna does belong with Ka-zar MM.

That leaves only few Super heroes:

and I think the only ones to possibly make it to Masterwork (and it is a long shot) are:
Killraven and Machine Man, but there is the 2001/Machine Man copyrights problem, so any one guess is as good as mine.

Cat/Tigra, Man-Wolf, Morbius, can all be done in one TPB.

Black Goliath, not enough for a TPB but perfect for one of those oversized $7.99 comics

That leaves only, Ms Marvel and SVTU as possible TPB series, and I agree Dr Doom inclusion would make a SVTU
collection more desirable.
I have to say that no matter how it will play out, there isn't much left out there to reprint from the short lived series of the 70s,
and that is kind of cool, I am pretty sure all of the above will be reprinted in the next few years.